As is known, an optical fiber is formed of a linear element comprising a core portion of relatively high refractivity and a clad portion of lower refractivity than that of said core portion and high transparency. This optical fiber has properties such that it conducts light incident on one end of the core portion to the other end with high efficiency. More particularly, light incident on one end of the core portion is efficiently led to the other end while repeating total reflection at the interface between said core portion and said clad portion many times.
Heretofore, an optical ornamental device utilizing said properties of optical fibers has comprised a light inlet end provided by one end of a bunch of optical fibers, the other end being developed to form a light emitting ornamental section according to a suitable ornamental pattern, said light inlet end being opposed to a screened light source, said light emitting ornamental section emitting light in dotted form. Such optical ornamental device is nothing more than a design such that light incident on the inlet end side of optical fibers is led to the outlet end side and emitted in dotted form from the outlet end side; thus, it is lacking in ornamental variegation.
On the other hand, optical fibers can be arranged to overcome total reflection at the interface between the core portion and the clad portion so as to allow part of light traveling in the direction of length to leak in intermediate portions of the optical fibers. Among known means for allowing part of light to leak in intermediate portions are (i) locally breaking the outer peripheral surfaces of optical fibers, (ii) locally breaking the interiors of optical fibers, (iii) forcing optical fibers to bend or curve, (iv) contacting a refractive solid with the outer peripheral surfaces of optical fibers. It is also known to apply said means to optical fibers to form light leakage portions in intermediate portions of the optical fibers, such optical fibers being then gathered to provide a surface-like light emitting device which allows light to leak in surface form. However, a conventional surface-like light emitting device based on said means is far from sufficient in the luminance of the surface-like light emitting section, so that it is of no use when used as an interior ornament illuminating device.